I am just venting there are so many complaints already

I just got a bill with a miscellaneous charge on it I called customer care and I was told it is for rates and taxes for 2019/2020 financial year which I was not charged for so they are charging me now. I asked why I was not billed in 2020 and in 2021 and only now in 2022 they decide to bill me when I have been paying my account in full every month and it’s always on zero balance once I pay. My issue is what stops them from coming back even next month and saying they want x amount of money because hey they forgot to bill me for something else. This is unacceptable and there is no statement for that charge on e-Tshwane website.